Pump structure



Patented Jan. 18, 1938 PATENT OFFICE PUMP STRUCTURE James Moore Evans, Detroit, Mich, assignor, by mesne assignments, to Grade Crossing Guard Corporation, Memphis, Tenn., a corporation of Tennessee Application August 2, 1935, Serial No. 34,323

2 Claims. (01. 103-41) The present invention relates to pumping mechanism, and more particularly to pumping mechanism constructed to provide a positive flow in one direction, and to permit a relatively free flow in an opposite direction.

It is an object of the present invention to provide a pump constructed to provide a positive fluid flow in one direction, and to permit a relatively free fluid flow in an opposite direction.

It is also an object of the present invention to provide apump structure embodying a pump chamber and selectively controllable means to permit a relatively free flow of fluid around the pump chamber.

It is also an object of the present invention to provide a pump structure embodying a p11 1p chamber and automatically controlled mechanism to permit a relatively free flow of fluid around the pump chamber.

It is also an object of the present invention to provide a pump of the last mentioned character in which the by-pass mechanism is responsive to the speed of operation of the pump.

It is also an object of the present invention to provide a pump structure embodying a pumping chamber, inlet and outlet chambers, and a selectively controlled valve to control a by-pass port between the inlet and outlet chambers.

It is also an object of the present invention to provide a pumpstructure embodying a pump chamber, and embodying valve mechanism disposedin balanced relation to the pump pressures to permit a flow through the pump independently of the pump chamber.

It is also an object of the present invention to generally improve the construction and operation of pump structures.

Other objects and advantages of the present invention appear in the following description and in the appended claims.

In the drawing, throughout which corresponding numerals are used to designate corresponding parts,

Figure 1 is a view in vertical, axial section in an illustrative embodiment of the present invention;

Fig. 2 is a view in vertical section taken along the line 22 of Fig. 1; and

Fig. 3 is a view taken along the line 3-3 of Fig. 1.

In accordance with the-illustrated embodiment of the present invention, the pump structure comprises generally a pump chamber, an inlet chamber, and an outlet chamber. The pump chamber comprises rotating mechanism to positively draw fluid from the inlet chamber and discharge it through the outlet chamber. In order to permit a relatively free flow of fluid through the pump structure without passing through the pump chamber, selectively controlled valve mechanism is provided to complete an auxiliary* connection between the inlet and outlet chambers. 'As illustrated, the inlet and outlet chambers are provided with a common separating wall, and the valve mechanism is positioned to open and close a port provided in such common separating wall.

The arrangement is preferably such that the selectively controlled valve responds to the speed of operation of the pump, being moved to a closed position when the pump is operating at or above a predetermined rate, and being moved to an open position when the speed of operation is below such predetermined value. As. illustrated,

the speed responsive control of the selectivelycontrolled valve is eiiected by governor mechanism suitably driven by the mechanism which drives the pump.

In accordance with the present invention also, the selectively controlled valve may be rendered independent of the pressures within the inlet and the outlet chambers. As illustrated, this relationship is accomplished by arranging the structure so that in any position of the valve, the parts directly associated therewith are subjected to equal and opposite components of the pressures within the inlet and outlet chambers, re-

spectively. With this arrangement, the valve is balanced in any given position with respect to the inlet and outlet chamber pressures.

The balancing of the selectively controlled valve, may be accomplished in various ways. As illustrated, a piston member rigidly connected to the valve is mounted for reciprocatory motion in an auxiliary cylinder formed in the pump structure. The cylinder area on one side of the piston communicates with one chamber, and the cylinder area on the other side of the piston communicates with the other chamber. The area presented by the piston is equal to the area presented by the valve when in closed position. In any position of the valve, accordingly, the pressure in either chamber. exerts equal and opposite forces on the respective valve faces.

The present invention also comprises an arrangement for providing forpressure relief within the pump structure. As illustrated, a spring pressed check valve is disposed to control a secvalve remains closed as long as the pressure within the outlet chamber is below a predetermined value, and moves to an open position when the Considering the above elements in more detail,

and referring to Figures 1, 2 and 3, casing I0 is formed to provide a pump chamber 12, an inlet chamber I 4, and an outlet chamber I6. A pump rotor l8, eccentrically mounted in chamber l2 on a drive shaft 20, and having a -plurality of pumping blades 22 pressed outwardly by a spring 24, draws fluid from inlet chamber l4 through port 26, and forces it into outlet chamber l6 by way of port 28. Chamber l4 communicates with a suitable source of fluid supply through opening 30, and chamber I 6 is provided with a suitable outlet passage 32.

Shaft 20, which may be driven in any suitable manner, is provided with a recessed section 2| over which rotor I8 is fitted. Spring 23 and plate 25 provide a somewhat resilient thrust bearing for the end of shaft 28.

Pumping blades 22 are slidably fitted in diametrically opposed recesses 21 formed in rotor l8. Spring 24, which biased blades 22 outwardly into engagement with the walls of chamber l2, passes through openings formed in rotor l8 and shaft 28.

The common wall 34 which separates chambers l4 and I6 is provided with an opening 36, which is normally closed by a spring pressed release valve designated generally 38. Valve 38 comprises a head 40, slidably fitted in a recess 42 formed in casing ID; a shank 44 slidably fitted in a sleeve 46 which is threaded into casing in and terminates in an external head 48; and a biasing spring 50 which surrounds shank 44 and bears against a shoulder formed thereon and a similar shoulder formed on sleeve 46. Rotation of head 48 inone direction or the othercauses sleeve 46 to move inwardly or outwardly with respect to casing l0, elongating or compressing spring'50 and correspondingly varying the contact pressure of valve head 40. As will be understood, if the pressure in chamber I6 exceeds the force exerted by spring 50, valve 38 is forced open, permitting the fluid to pass freely between chambers I4 and I6, through opening 36, without passing through pump chamber l2.

Wall 34 is also provided with a second opening 52, which affords communication between chambers l4 and IS. A valve 58, disposed to engage the margins of opening 52 to close the latter, is connected to a piston 68 by a central post 62.

Piston 60 is slidably fitted in a cylinder 54 formed on the interior of casing l0, axially concentric with opening 52. A passage 56 connects chamber I 6 and cylinder 54. The diameters of piston 68, cylinder 54 and opening 52 are the same, but it is noted that valve 58 is somewhat larger than the opening 52. When the valve 58 is closed accordingly a, predetermined pressure differential exists which urges it to the closed position. When the valve 58 is open on the other hand the pressures on opposite sides thereof are substantially equal, and differ only by an amount which is caused by the cross sectional area of rod 64.

The shank 64 of valve 58 extends through casing Ill and into the interior of a governor housing 66, which is suitably secured to, casing ill by studs 68. A spring 18, suitably secured to the interior of housing 66 by studs 12, surrounds a governor sleeve 14 which is tightly fitted on shaft 20, and is connected at its upper end to shank 20, and. hence of the pump, is below a certain' value, the centrifugal governor mechanism designated generally 80, forces spring 10 to the left, in which position it actuates valve 58 to the open position. When the pump speed exceeds the predetermined value, however, governor mechanism 80 is retired, and spring 18 is rendered effective to close valve 58. As will be understood, the above mentioned balanced condition of valve 58 permits the use of a relatively light and simple actuating member, and the above mentioned pressure differential which exists when the valve is closed, aids spring 18 in maintaining the valve in the closed position.

Although governor mechanism 80 may be of any conventional type arranged to function as above described, it preferably comprises the sleeve 14, tightly fitted on shaft 28; an auxiliary sleeve 84 slidably fitted on sleeve 14 and having projecting shoulders disposed for engagement by the end sections 82 of the two governor arms 86; a pair of weights 88 connected to arms 86 and slidably positioned within a frame 98 which serves to guide the movements thereof and is tightly fitted on sleeve 14; and a pair of biasing springs 92, disposed to engage pins 94 which pass-through weights 88, and serve to bias the latter inwardly. As will be understood, upon rotation of shaft 28, governor 88 rotates correspondingly, and weights 88 are centrifugally forced outwardly within frame 90. This motion of weights 88 causes arms 86 to move sleeve 84 to the right as viewed in Fig. 1. In response to this spring 10 moves to the right, closing valve 58 and moving collar 96 to the right. If the speed of shaft 20 falls below a predetermined value, springs 82 force weights 88 inwardly, causing collar 96 to move to the left. This action force's spring 10 to the left, re-opening valve 58.

With reference to the operation of the pump as a unit, it will be understood that opening 88 communicates with a. suitable source of fluid supply, and that opening 32 communicates with a suitable discharge line. With pump rotor 58 at rest, valve 58 occupies the open position as previously described. Under these conditions, fluid is enabled to pass through the pump casing, by way of opening 52, without passing through pump chamber l2. This flow may be in either direc-' tion through the pump. In application of the pump to reciprocatory systems, such for example as disclosed in the co-pending application of the present applicant, Serial No. 34,322, filed August 2, 1935, and assignedto the same assignee as the present application, in which a corresponding pump is utilized to actuate a hydraulic ram, the flow of the fluicl'is ordinarily in a direction opposite to that produced when the pump is in operation. In such instances, opening 52 permits a return movementhf the fluid.

If the pump is placed in operation, the rotation of rotor l8 and of blades 22 positively draws fluid from inletchamber l4 through pump chamber l2 into outlet chamber I 6. As long as the speed of the pump remains below the previously mentioned predetermined value, valve 58 remains open so'that the fluid thus circulated passes be-. tween chambers l4 and I 6 by way of opening 52, and substantially no pressure is developed by the pump in either of the lines connected to inlet and outlet openings 20 and 32. As will be understood,

valve 58 may be caused to close at any desired the fluid circulated through the pump is drawn from the inlet passage and passes out through the outlet passage, the pressure developed being determined by the pump characteristics.

If the speed of the pump falls below the predetermined value, governor mechanism 80 actuates valve 58 to the open position, permitting the previously -mentioned circulation of the fluid within the pump. Upon the opening of valve 58, the pressure developed by the pump in the line connected to passages 30 and 32 falls to substantially zero. If the fluid in these lines is subjected to any reverse pressure, such reverse pressure results in a, reverse flow of the fluid through the pump by way of opening 52.

If at any time during the operation of the pump, the pressure within outlet chamber l6 exceeds a predetermined value, relief valve 38 is actuated to the open position, connecting inlet and outlet chambers l4 and I6 respectively by way of openings 36, again permitting a circulation of the fluid within the pump.

Although a specific embodiment of the present invention has been described,'it will be evident that various modifications may be made in the form, number and arrangement of parts without departing from the spirit or scope thereof. The described embodiments, accordingly, are to be considered inan illustrative and not in a limiting sense.

What is claimed is:

1. In a pumping mechanism, a casing provided with outer enclosing walls and an interior wall to define separate inlet and outlet chambers disposed on opposite sides of the interior wall, a rotary impeller in said casing for transmitting fluid between said inlet and outlet chambers, said impeller being provided with a shaft projecting outwardly of said casing, said interior.

wall having an opening therein to form a by pass connection between said chambers, a valve movably supported in said casing for opening and closing said opening and having an operating rod projecting outwardly of said casing, and a speed responsive means on said shaft having an operating connection between the shaft and the rod externally of the casing whereby said valveand closing said opening and having an operating rod projecting outwardly of said casing, means associated with said valve for subjecting it when closed to a fluid pressure differential acting in a direction to hold it closed, and a speed responsive means on said shaft having an operating connection between the shaft and the rod externally of the casing whereby said valve will be closed upon attainment of'predetermined speed.

JAMES MOORE EVANS. 

